Reducing carbohydrates are present in a wide variety of foods, including fruits, breads, and dairy products (e.g., milk and cheese), among many other kinds of food. These reducing carbohydrates include reducing sugars, such as glucose, galactose, lactose, and other saccharides having an unsubstituted anomeric center, that add flavor and metabolizable energy to the food. However, reducing sugars in food ingredients also present challenges in the preparation of cooked (e.g., baked) foods.
The heating of reducing sugars often leads to non-oxidative, non-enzymatic browning of the food through processes such as carmelization (i.e., the direct heating of carbohydrates in the presence of acids or salts), and Maillard browning (i.e., the interaction of amino group containing compounds such as proteins with the reducing sugar and water). Maillard browning is a common problem in the cooking of breads and dairy foods where the starting ingredients invariably include reducing sugars, amino acids (e.g., L-lysine, L-arginine, L-histidine, etc.) and water, mixed together and reacting at elevated temperatures to cause the browning.
The control of Maillard browning is important for several reasons: Overly browned foods may be aesthetically undesirable and unappetizing, especially when the dark colors are accompanied by unwanted odors and flavors. Also, the reactions that produce Maillard browning reduce the quantity of essential amino acids in the food, reducing its overall nutrient value.
Undesirable Maillard browning may be controlled by changing the water content in the starting ingredients of the food, where less water generally reduces the degree of browning. For liquid ingredients, Maillard browning may be reduced by lowering the pH (i.e., increasing the acidity) of the ingredient. The browning may also be reduced by lowering the cooking temperature of the food. Finally, food additives such as sulfur dioxide or sulfites may be added prior to or during cooking to inhibit Maillard browning.
Unfortunately, all of these means of controlling Maillard browning create other problems when cooking the foods, including overly dry baked goods due to removal of water, and sour tastes in foods due to lowering the pH. Thus, there remains a need for new approaches for controlling Maillard browning that do not add unnatural chemical additives to the food, or adversely affect the taste and quality of the food.